Support Effect on the Water Gas Shift Activity of Chemical Vapor Deposition-Tailored-Pt/TiO₂ Catalysts

Abstract

In contrast to most wet chemical synthesis routes, chemical vapor deposition (CVD) offers many degrees of freedom for the structuring of Pt nanoparticle catalyst systems, which is a prerequisite for the examination of structure−function correlations in heterogeneous catalysis. Two different suitable metal−organic Pt precursors [MeCpPtMe 3 and novel PtMe 2 (iBu-COD)] were employed to generate highly defined, very narrowly distributed Pt nanoparticles with high active surface areas on well-specified TiO 2 supports of differing surface properties. The TiO 2 supports and the Pt nanoparticles were thoroughly characterized and tested in the water gas shift reaction. The influence of the support particle size and its surface chemistry (hydroxyl groups) as well as the nature of the metal−organic precursors used on the water gas shift (WGS) activity were investigated by nanotechnological methods within this study. A further modification of the support material was done by Na deposition. This catalyst was found to be a highly efficient WGS catalyst with an increase of the catalytic activity by a factor of 3 compared to the nonmodified system.

Engineering Stable Surface Oxygen Vacancies on ZrO2 by Hydrogen-Etching Technology: An Efficient Support of Gold Catalysts for Water-Gas Shift Reaction

“…For instance, both precious metals (Pt, Rh, Pd, Au, Ir, Ru, etc. ) , and nonprecious metals (Cu and Ni) were supported on miscellaneous supports, such as TiO 2 , − CeO 2 , − ZrO 2 , − Mo 2 C, FeO x , , Al 2 O 3 , CeO 2 –TiO 2 , and CeO 2 –ZrO 2 . − Among them, the supported gold catalysts usually present high activity and selectivity . Meanwhile, ZrO 2 is regarded as a promising support because of its excellent thermal stability, low cost, and tunable physicochemical properties (e.g., surface acidity/basicity and redox properties), which can be modified by using different synthesis methods and adding different dopants. , Thus, Au–ZrO 2 should be potential catalysts to deliver high WGS activities.…”

Hydrogen-Etched TiO2−x as Efficient Support of Gold Catalysts for Water–Gas Shift Reaction

“…To develop new and more efficient WGS catalysts, supported catalysts have been believed to be good candidate. For example, both precious metals (e.g., Pt, Au, Pd, Rh, Ir or Ru) [2,3] and cheap transition metals (e.g., Cu or Ni) [4,5] were deposited on various supports including TiO 2 [6][7][8][9][10][11][12][13][14][15][16][17], CeO 2 [18][19][20][21][22][23], Mo 2 C [24][25][26], FeO x [27][28][29], Co 3 O 4 [30], Al 2 O 3 [31,32], ZrO 2 [33,34], CeO 2 -TiO 2 [35], CeO 2 -ZrO 2 [36,37] and CeO 2 -La 2 O 3 [38]. Au-TiO 2 catalysts have been given considerable attentions for WGS activities, due to the high activity and low side reactions of dispersed Au [38], and some advantages of TiO 2 supports (e.g., low price, easy preparation, adjustable properties and strong interaction with active metal).…”

Understanding the Nature and Activity of Supported Platinum Catalysts for the Water–Gas Shift Reaction: From Metallic Nanoclusters to Alkali-Stabilized Single-Atom Cations

“…They further demonstrated that an abundance of Pt nanoparticles was formed on all these supports in the absence of alkali elements and these nanoparticles exhibit a lower WGS activity than their single Pt 2+ counterparts stabilized by alkali ions. The promotional effect of alkali addition was also observed for Pt nanoparticles on other supports. ,,,− Earlier studies on alkali-doped Pt/CeO 2 catalysts by Davis and co-workers , suggested that (i) the alkali dopants are located on both the platinum and ceria components and (ii) they electronically modify both the support and Pt species. The promotional effect of alkali on the Pt/TiO 2 catalyst was attributed to the alkali-induced reduction of Ti 4+ surface species by creating oxygen vacancy sites at the Pt/TiO 2 interface sites .…”